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GASES DISSOLVED IN THE WATERS OF 
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From BULLETIN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908 
Proceedings of the Foiirth International Fishery Congress : : Washington, 1908 




WASHINGTON :::::: GOVERNMENT PRINTING OFFICE 



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Digitized by the Internet Archive 
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http://www.archive.org/details/gasesdissolvedinOObirg 



GASES DISSOLVED IN THE WATERS OF 
WISCONSIN LAKES ^ ^ ^ ^ ^ 

From BUIvIvETlN OF THE BUREAU OF FISHERIES, Volume XXVIII, 1908 
Proceedings of the Fourth International Fishery Congress : : JVashington, ipoS 




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BUREAU OF FISHERIES DOCUMENT NO. 718 
Issued May, 1910 



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GASES DISSOLVED IN THE WATERS OF WISCONSIN LAKES 



By Edward A. Birge 

Secretary Wisconsin Commission of Fisheries 



Paper presented before the Fourth International Fishery Congress 
held at Washington, U. S. A., September 22 to 26, 1908 



GASES DISSOLVED IN THE WATERS OF WISCONSIN LAKES. 



By EDWARD A. BIRGE, 

Secretary Wisconsin Comtnission of Fisheries. 



In the following paper I propose to sketch briefly a small part of the work on 
lakes which the Wisconsin Geological and Natural History Survey has been 
carrying on during the past four seasons. During 1907 and 1908 our investi- 
gations have been aided by a grant of money from the United States Bureau 
of Fisheries, which has enabled us to extend our field work much more than 
would have been possible without this assistance. 

LAKE DISTRICTS OF WISCONSIN. 

The accompanying sketch map (fig. i) roughly indicates the position of 
the lakes that have been studied. Wisconsin contains many hundreds of small 
lakes, most of them lying in the moraines and found in hollows occasioned by 
the melting of blocks of ice left during the glacial period. They occur in three 
pretty well-defined districts, in the southeastern, the northeastern, and the 
northwestern parts of the state. The water of the lakes in each district, though 
varying much, shows a very definite general character, especially in the matter 
of dissolved carbonates. 

The southeastern lake district, as studied by us, extends from Waupaca 
on the north to Lake Geneva on the south, and from the lakes at Madison to 
Lake Michigan. Nearly 50 lakes in this district have been studied by our 
survey, and almost without exception they contain considerable quantities of 
dissolved carbonates, represented by 30 cubic centimeters to 50 cubic centi- 
meters or more of carbon dioxide. Most of the work has been done upon these 
lakes. Very numerous observations have been made upon Lake Mendota at 
Madison, the headquarters of the survey, and some htmdreds of series of deter- 
minations have been made on this lake at all seasons of the year. Much less 
frequent observations have been made on a dozen or more other lakes in the 
same region, giving a general picture of the annual cycle of gas changes of these 
lakes, though not in the same detail as for Lake Mendota. '^ 

a The diagrams accompanying this paper have been selected from a great number which have 
resulted from the work of this survey, and are intended to illustrate some points in the distribution of 
temperature, of the various gases, and of dissolved carbonates of lime and magnesium in the waters of 
Wisconsin lakes. In all diagrams the vertical spaces represent the depth in meters. The horizontal 
spaces represent either degrees centigrade in the case of temperature, or cubic centimeters of gas per 
liter. The line marked " T" indicates the temperature; oxygen is marked " O " ; nitrogen, " N " ; carbon 
dioxide, "C"; and carbonates, "Cb." In the diagrams which show nitrogen, both*his gas and oxygen 
were determined by boiling. In those without nitrogen, the oxygen was determined by titrating 
according to Winkler's method. The alkalinity or acidity of the water were determined by titrating 

1275 



1276 BULLETIN OF THE BUREAU OF FISHERIES. 

In the northeastern part of the state is a district somewhat triangular in 
shape, measuring roughly some 30 miles on each side, and containing several 




3. I. — Sketch map of Wisconsin, showing lake distric 
directly north of "G". The Oconomowoc di 
ary. Hammills Lake in northwestern Wisconsin 



. Green Lake lies 
the southern bound- 



with Standard solutions of HCl or Na^COg, with phenolphthalein as an indicator. The result is expressed 
in the diagrams in cubic centimeters of CO2 per liter, acidity being shown as free CO,, while alkalinity- 
is represented by platting the number of cubic centimeters of COo that would be required to bring about a 
neutral reaction. Where the line indicating the CO2 passes to the left of the zero line, it indicates that 
the water is alkaline. 

The amount of dissolved carbonates was determined by titrating with HCl, with methyl orange as 
an indicator. It is represented in the diagrams by the number of cubic centimeters per liter of CO2 set 



GASES. IN WATERS OP WISCONSIN LAKES. 



1277 





8101 



N 34 36 38 40 

14 16 16. ^0 22 



hundred small lakes. About 60 of the more important and deeper lakes 
in this region have been studied during the summer. The survey has found 
that the month of August and the early part of September represent the 
critical period for the distribu- 
tion of gas in lakes, and that „ ^n^ 9 
from observations made at this °r 
time the general history of a lake 
may be inferred when the cycle 
is known in detail from a num- 
ber of lakes which may serve as 
standards. The lakes of north- 
eastern Wisconsin contain, in gen- 
eral, soft water, the carbonates 
being much lower than in the 
southeastern lakes — frequently 
not more than one-sixth as great 
and not infrequently less than 
one-tenth. 

The lakes in the northwestern 
district are scattered in two some- 
what ill-defined elongated seiies 
extending north and south for a 
distance of 70 miles or more. 
Between 50 and 60 of these lakes 
also have been examined. Their 
water is intermediate in character 
between that of the two other 
districts, the content in carbon- 
ates averaging nearly one-half 
as great as that of the south- 
eastern lakes. 



"iG. 2. — Lake Mendota. Vertical distribution of gases, carbonates, 
and temperature, January 26, 1906. C, carbon dioxide ; C 
ates of lime and magnesia; N, nitrogen; O, oxygen; T, tempera tu 
See footnote. 



GASEOUS CHANGES IN LAKE MENDOTA. 



Let me begin my account by a short sketch of the cycle of changes in Take 
Mendota. Figure 2 shows the condition under the ice in early winter. The 

free from the monocarbonates. Since, in the lakes of southeastern Wisconsin, the amount of dissolved 
carbonates is considerable, the numeration of the horizontal scale is interrupted in order not to make 
the diagram too large. For instance, the numbers at the top of figure 2 change abruptly from 22 to 34. 
The larger numbers refer solely to the line Cb, indicating the number of cubic centimeters of COj 
represented in the monocarbonates. A similar arrangement will be seen in other diagrams. 

The points at which observations were taken are indicated by small circles in the lines of the dia- 
grams. The lines are drawn directly from one point of observation to the next, no attempt being 
made to round ofT the curves. 



1278 BUIvLETiN OF THE BUREAU OP FISHERIES. 

temperature is nearly the same at all depths, rising from less than one degree 
just below the ice to something over one degree at the bottom. The water con- 
tains about 9 cubic centimeters of oxygen per liter, except in the bottom, where 
it has begun to disappear under the action of decomposition. Nitrogen is present 
to about the amount required to saturate water at the given temperature. The 
reaction of the water is neutral or slightly alkaline at all depths. Carbonates 

are present to an amount rep- 
resented by about 38 cubic 
centimeters of carbon dioxide 
per liter. 

As the winter advances (fig. 
3) some changes occur under 
the ice . The temperature rises 
slowly at all depths, but most 
rapidly at the bottom. Slow 
decomposition goes on in the 
deeper water, where also the 
greater part of the fish are 
found. There thus results a 
reduction of the amount of 
oxygen, which may nearly or 
quite disappear at the bottom, 
and a corresponding develop- 
ment of carbon dioxide, so 
that as winter advances the 
bottom water may contain 
considerable quantities of free 
carbon dioxide. The reaction 
of the upper water becomes 
much more markedly alkaline 
than in the early winter, a 
change probably due to the in- 
fluence of the growing plants. The carbonates may or may not decrease in the 
water immediately below the ice. If a diminution is found (and such decrease 
may be very pronounced, as in fig. 4), the change is due to the accumulation 
beneath the ice of water resulting from the melting of the ice or snow and 
containing, therefore, less dissolved matter than the water of the lake usually 
holds. As the season advances a rapid growth of algae may take place beneath 
the ice, resulting in a considerable increase of the oxygen, which may carry 
it beyond the point of saturation. This increase is usually accompanied by a 
considerable increase in the alkalinity of the water (fig. 4) . 



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GASES IN WATERS OF WISCONSIN LAKES. 



SPRING AND SUMMER. 

When the ice has disappeared in the spring (fig. 5) , the water is once more 
mixed throughout the entire depth, and uniform conditions are again estab- 
Hshed. The reaction becomes almost or quite neutral. Oxygen is present to 
about the point of saturation, although, in figure 5, some trace of the winter's 
diminution of oxygen is still present at the bottom. Carbonates and nitrogen 
are distributed about uniformly at all depths. As the spring advances and the 
algae begin their spring growth, the reaction of the water becomes increasingly 



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Tk;. 4. — Lake Mendota, March 29, 1906. 

alkaline. (Fig. 6.) The temperature rises, and soon the surface gains so 
rapidly in warmth that the wind is unable to distribute the surface water 
throughout all depths; the circulation becomes increasingly restricted, and sum- 
mer conditions begin to develop. The temperature curve (fig. 7) shows a 
marked difference between surface and bottom temperatures, and indicates a 
temporary thermocline at the depth of 10 meters or more. Corresponding to 
this stratification of the water and consequent shutting off of the lower water 
with direct contact with the air, the oxygen in the lower water begins to decline 



I28o 



BULLETIN OP THE BUREAU OF FISHERIES. 



and free carbon dioxide begins to appear there. This process is accentuated as 
summer approaches. (Fig. 7 and 8.) The amount of free carbon dioxide 
increases, the thickness of the stratum of the water whose reaction is acid 
increases also, and the oxygen steadily and rapidly declines in the lower water. 
By the early part of July the permanent summer conditions of temperature are 
found. (Fig. 8.) The regular summer thermocline is found lying, in general, 
between 5 meters and 10 meters. Oxygen has disappeared wholly from the bot- 
tom waters, and is rapidly going from 
all parts of the lake below the ther- 
mocline. The water has divided into 
an upper warm stratum containing 
an abundance of oxygen and with an 
alkaline reaction, and a lower, colder 
layer with free carbon dioxide, and 
little or no oxygen except in the ex- 
treme upper part. 

LATE SUMMER AND AUTUMN. 

By the first of August this con- 
dition has reached its maximum. 
(Fig. 9) . The lake contains no oxy- 
gen below a depth of 10 meters. 
Above that level, in the warm water 
and in the uppermost part of the ther- 
mocline, there is abundance of oxygen 
for animal life. Beneath that depth 
no active animal life is found in the 
water,'' though the inhabitants of the 
mud remain alive through this period, 
some of them in an inactive condi- 
tion and some in a partially active 
state . The carbonates show the char- 
acteristic summer condition, in which 
the upper water contains a smaller amount than the lower, the transition coming 
in rapidly at the thermocline. This condition persists through August and early 
September for a period varying with the warmth of the season. As the tem- 
perature of the water begins to fall, the thermocline moves downward under 
the action of the wind, and this process increases the extent of circulating water 
and in like degree the thickness of the layer containing oxygen. Figure 10 
illustrates this condition in early October. The cold weather and winds which 
are apt to occur at about this time soon bring about a complete mixture of the 

« Except Corethra larvae, whose presence is an apparent rather than a real exception. 



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—Lake Mendota, April 8, 1906. 



GASES IN WATERS OF WISCONSIN LAKES. 1 28 1 

water (fig. 11) ; and with it returns the condition of uniformity which we found 
at the opening of winter. From this time until the lake freezes the temperature 
declines almost uniformly at all depths; the amount of oxygen increases as the 
capacity of the water to hold it rises with the fall in temperature; and the 
water becomes almost or quite neutral as the vigor of the growing algse 
declines and as decomposition becomes slower in the cooling water. 

From this brief account it is plain that the cycle of gas changes in Lake 
Mendota is a very important factor in determining the conditions and possibilities 
of life in that lake. Here is an inland lake, one of the largest in Wisconsin, 



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Fig. 6. — Lake Mendota, May 4 



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COT 

. — Lake Mendota, May 21 



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about 9 kilometers in length and 6 kilometers in breadth, with a maximum 
depth of 24 meters and an average depth of about 12 meters, the lower half 
of whose water is wholly uninhabitable during middle and late summer and 
early fall. This water in the early spring is saturated with oxygen, as is the 
lower water of all lakes, but the supply is not great enough to meet the demands 
which are made upon it. The lake is peculiarly rich in plankton, and the 
decomposition of the great amount of animal and vegetable debris which is 
showered down from the upper waters into the lower soon exhausts the oxygen 
supply and renders the lower water unfit for the maintenance of higher life. 



1282 



BUIvIvETlN OF THE BUREAU OF FISHERIES. 



Thus the vital conditions in one part of the lake very sharply limit the possi- 
bilities of life in another portion. None of those fish which demand a refuge 
in the cold bottom water during the summer can live in Lake Mendota, nor is 
it possible to find there those members of the plankton which belong only in 
the deeper and colder water. 

It is perhaps unfortunate for some reasons that Lake Mendota was necessarily 
the lake on which the most numerous observations were made, since this lake 
offers an extreme case in the matter of loss of oxygen from the lower water. 
The oxygen disappears more quickly and fully than in any other Wisconsin lake 



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Fig. 8. — Lake Mendota, July 2, 1906. 

of approximately equal size and depth. The area of the lake is so large that the 
bottom water has necessarily a relatively high temperature, and the plankton 
is so abundant that the lower water is continually receiving great quantities of 
decomposable matter. Moreover, the thermocline lies comparatively deep 
because of the large size of the lake, so that the volume of the cooler water is 
correspondingly reduced. All of these causes combine to make the disappearance 
of the oxygen very complete and unusually rapid. This lake therefore affords 
less opportunity than do other bodies of water for the study of the process in its 
details. 



GASES IN WATERS OF WISCONSIN LAKES. 



1283 



GASES AND CARBONATES OF OTHER LAKES IN SOUTHEASTERN WISCONSIN. 

We may contrast the summer conditions in Lake Mendota with those that 
obtain in the deepest inland body of water in Wisconsin, Green Lake. This 
has a maximum depth of 72 meters, with length of about 12 kilometers and a 
breadth of 4 kilometers. Figure 12 shows the conditions found in Green Lake 
on October 4, 1906. The volume of water is so great that summer conditions 
of temperature still remain, and cooling has proceeded to no great depth. The 
water shows the characteristic summer condition of an alkaline upper stratum. 



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Fig. 9. — Lake Mendota, August i, 1906. 

with the cooler water acid. The dissolved carbonates are low in the warmer 
waters, rapidly increasing at the thermocline, and then remaining nearly con- 
stant till the bottom of the lake is almost reached, where there is again an 
increase. The oxygen shows a marked diminution in the thermocline (ii 
meters to i6 meters) ; it then slowly increases in quantity with the depth until 
a maximum is reached at about 40 meters, which remains for some 10 meters; 
and the amount of the gas then declines until it is nearly or quite exhausted at 
the bottom. The diagram shows plainly the effect of life and death on the 
oxygen where it is found in abundance in a large volume of water. The oxygen 



BULLETIN OF THE BUREAU OF FISHERIES. 



1284 

curve shows that two of the regions where chemical action is going on most 
vigorously are the thermocline and the bottom water. The accumulation and 
decomposition of the plankton in the lower water is a sufficient explanation 
for the changes which take place there. The reduction at the thermocline is 
apparently due to the fact that the algae, as they begin to die and sink, often 
remain for some time at the thermocline. The cool water apparently causes 
their life to be prolonged, and while certain parts of the filaments are dead 
and decomposing, others still retain sufficient vitality ,to keep the plant from 
^. sinking. When this period is 

.0. - - ,0 _ ._._.. .T _ 30 32 34 36 38 40 passed, the plant sinks steadily 

and rather rapidly to the bot- 
tom, thus consuming compara- 
tively Httle oxygen on the jour- 
ney. Many forms of plankton 
animals also accumulate in the 
thermocline, finding there more 
food than in any other part 
of the cool water. Both these 
causes, then, lead to a diminu- 
tion of the oxygen at this point. 
It must not be supposed that 
there has been no loss of oxygen 
in the lower water where it is at 
a maximum. In early spring 
this water would have corftained 
between 8 cubic centimeters and 
9 cubic centimeters per liter, so 
that at least one-third of the 
original stock has been con- 
sumed. 

Green Lake is the only lake 
in Wisconsin that shows so small 
a reduction of the oxygen of the 
lower water. Lake Geneva, near the southern boundary of the state, has about 
the same dimensions as Green Lake; it is the second deepest lake in the State, 
having a depth of 41 meters. The late summer conditions are shown in figure 
13, where the same general facts are visible as in Green Lake; but the oxygen is 
much more reduced and shows only a trace, or is altogether absent, from the 
depth of 33 meters to the bottom. In North Lake, one of the Oconomowoc 
group, consumption of oxygen at the thermocline goes on more rapidly, and 
sometimes leads, as is shown in figure 14, to the disappearance of the oxygen 
from that stratum, while some of the gas still remains at a greater depth. 



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—Lake Mendota, October 8 



GASES IN WATERS OF WISCONSIN LAKES. 



1285 



This lake has an area of about 51 hectares (126 acres) and a depth of about 
22 meters. It contains an abundance of oxygen in the water above the ther- 
mocHne; then follows a stratum in which the gas has almost or quite disap- 
peared; then comes one containing a small amount, but sufficient for the 
maintenance of a large number of plankton animals; and beneath this to the 
bottom the water contains no oxygen. A little later, in September, all of the 
oxygen will have disappeared from the lower water, and the region beneath the 
thermocline will become uninhabitable by animal life. 

LAKES OF NORTHEASTERN WISCONSIN. 
All of these illustrations are taken from the lakes of southeastern Wiscon- 
sin, where, as shown by the diagrams, the dissolved carbonates are present 
in large quantities, and where the 

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28 30 32 J4 36 



plankton life is correspondingly abun- 
dant. In the lakes of northeastern 
Wisconsin, where the carbonates are 
low, the average quantity of plank- 
ton is much less than in the hard- 
water lakes. It is not true that the 
plankton of every soft-water lake is 
smaller than that of every hard- water 
lake. The lakes of both types differ 
among themselves very greatly, but on 
the average the statement is entirely 
correct. European observers have 
found the same thing for the fish in 
the lakes of Switzerland that we have 
found for the plankton in Wisconsin. 
We have also found that there are 
fewer fish in the northern lakes than 
in the southern, hard- water lakes. In 
these northern lakes, therefore, with 
their poorer plankton, the oxygen per- 
sists longer than in the southern ones. 
It may disappear entirely , but it usually 
lingers late, and in the deeper lakes it 
is apt to remain throughout the season. 

The diagrams of Thousand Island Lake and Stone Lake (fig. 15, 16) show 
the summer condition in two of the larger and deeper lakes of this type. The 
carbonates in both are low, representing about 9 centimeters and 3 cubic 
centimeters of carbon dioxide, respectively. The upper water is acid, or nearly 
neutral, the acidity increasing below the thermocline. The oxygen curve of 
Thousand Island Lake closely resembles that of Green Lake, having a depression 



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—Lake Mendota, October ii, 1906. 



1286 



BUI^IvETlN OF THE BUREAU OF FISHERIES. 



at the thermocline, and an increase in the deeper waters, followed by a gradual 
decrease to the bottom, where the oxygen is nearly or quite exhausted. This 
Thousand Island Lake is one of the lakes in northeastern Wisconsin that contain 

lake trout {Cristivomer namaycush). 
The fish inhabits the bottom water 
during the summer, and seems to be 
found native only in lakes which carry 
an abundance of oxygen to the bot- 
tom. The oxygen curve of Stone 
. Take (fig. 1 6) shows another interest- 
ing fact which is observable in many 
inland lakes, namely, an increase of 
oxygen in the upper part of the ther- 
mocline. This is due to the presence 
of algae at this depth, which still re- 
ceive sufficient light to manufacture 
starch, and liberate oxygen in that 
process. This phenomenon is very 
commonly found in our lakes, but by 
no means universally. The crops of 
algae, which produce oxygen, are not 
necessarily continuous ; nor is oxygen 
produced in quantities beyond con- 
sumption at all periods of their growth. 
The thermocline may lie so deep or 
the water may be so opaque that 
algae in the cool water do not get 
light enough to enable them to produce 
starch. Neighboring lakes, therefore, 
which seem quite similar, may or 
may not show this rise of the oxygen. 
In the same lake it may appear and 
disappear during the season, and 
although usually present at a corre- 
sponding time in successive seasons 
may vary greatly in amount. One 
common result of this process is the 
using up, at this point, of the carbon 
dioxide, the fact being shown by a reduction of the acidity, or an increase 
in the alkalinity, of the water. The contrast between the carbon dioxide 
curves in Thousand Island and Stone lakes is sufficiently noteworthy, and this 
difference is apparently due to the activit}'- of the algae at a depth of 9 meters 




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— Green Lake, 



6 4 2 2 4 



GASES Ii-^ WATERS OF WISCONSIN LAKES. 1 287 

and 10 meters in Stone Lake, and the consequent using up of the supply of free 
carbon dioxide. 

MANUFACTURED OXYGEN. 

In other lakes this process goes on much more vigorously than it did in 
Stone Lake. An illustration may be given from Beasley Lake, a little body 
of water in the Waupaca chain (fig. 1 7) , where the oxygen at the thermocline 
rises to the maximum of about 15 cubic centimeters, and where its presence 
is accompanied by a marked increase of the alkalinity of the water. 

It must be remembered that ^^ 

both the amount of oxygen and 
of alkalinity represent the al- 
gebraic sum of numerous com- 
plicated processes . The amount 
of oxygen is determined not 
only by the quantity manu- 
factured, but also by that con- 
sumed, and the quantity or 
deficiency of carbon dioxide 
depends on the relation of the 
rate of the manufacture of 
starch to the rate of the de- 
composition of the plankton. 
The two processes are not nec- 
essarily parallel, and we not in- 
frequently find, as is shown in 
figure 18, a great excess of 
oxygen, while the carbon di- 
oxide curve shows no traces of 
the process which has manufac- 
tured it . In the soft- water lakes 
whose reaction is usually acid, 
the manufacture of oxygen in 
the cooler water may cause a change in the reaction of the water. This is 
illustrated by Silver Lake (fig. 19), a small pond in northeastern Wisconsin, 
where the oxygen maximum occurs at 7 meters, and at the same depth the 
reaction changes from a positive acid to an equally positive alkaline one. It 
returns to a slight acidity at 9 meters, and from this point the amount of free 
carbon dioxide rapidly increases. 

In the smaller and shallower lakes the presence of this manufactured oxygen 
at the thermocline region is often of great importance in extending the inhab- 
itable region. Beasley Lake is perhaps the best illustration of this fact. The 



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Fig. 13. — Lake Geneva, September 2 



BULLETIN OF THE BUREAU OF FISHERIES. 



lake contains a great amount of fermentable material, and the oxygen disappears 
from the bottom water early in the spring. The lake is so small that the ther- 
mocline lies very close to the surface, remaining at 4 meters or above until late 
in the summer. Were it not for the manufactured oxygen, the entire body 
of water below the thermocline would be uninhabitable. The maintenance of 
the stock of this gas by the presence of the algae doubles the thickness of the 
habitable stratum during the summer and the early part of the autumn. Figure 
1 7 also shows the effect of the manufacture of oxygen on the dissolved carbon- 
ates; but that matter is too complex to be discussed here. 

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—North Lake, east part, July 30, 1906. 



I have spoken of Thousand Island Take as a characteristic " lake-trout lake." 
So far as our observations go, the lake trout in northeastern Wisconsin is found 
only in lakes of this type; yet observations made in the summer of 1908 in north- 
western Wisconsin show that the fish can exist in lakes of a type which would 
seem to be unfavorable to it. I give a diagram of the conditions in Hammill's 
Lake (fig. 20) , a small body of water in northwestern Wisconsin, which contains 
a few lake trout that have been introduced. Their presence in the lake shows 
that they can exist in a body of water in which the oxygen extends some distance 



GASES IN WATERS OF WISCONSIN LAKES. 1 289 

into the cooler stratum, although the bottom water is practically or wholly devoid 
of the gas. Their presence in small numbers shows that such a lake is not suited 
to the species, and that, while it can adjust itself and survive under these unfa- 
vorable conditions, it is unable to thrive. It is not known whether it spawns 
tmder these conditions. There can be little question that the continuance of the 
species in this lake is due to the fact that the cool water still retains a certain 
amount of oxygen throughout the season. 



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Fig. 16. — Stone Lake, 2 



CONCLUSIONS. 



I have selected for illustration these series from among the hundreds of 
similar observations that have been made by the Wisconsin Geological and Nat- 
ural History Survey. I have not attemped to give any complete picture of the 
story of the gaseous changes in any lake, and many of the most important rela- 
tions and results have been left unmentioned. I have brought these cases to 
your attention in order to illustrate two conclusions which are of importance. 
The first is that the cycle of the gaseous changes in a lake illustrates more 
readily and more conspicuously than perhaps any other facts could do what 
maybe called the "annual life cycle" of the individual lake, showing both the 



1 290 



BUIvLETiN OF THE BUREAU OF FISHERIES. 



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underlying resemblances of that cycle as found in different lakes and also some 
small part of the infinite variation in its details. These diagram.s from late 
summer represent the culminating point of an annually recurrent series of defi- 

nite changes through 
C 36 38 40 42 44 which the lakes pass with 

the season as certainly as 
the season returns. These 
changes result from the 
interrelation of the living 
beings of the lake with an 
environment strictly lim- 
ited in its space and con- 
taining only definite 
amounts of food and of 
oxygen, to which only 
small additions can be 
made from the outside. 
The story of these changes 
is legible to him who will 
closely follow it. Its de- 
tails differ, indeed, in each 
lake from those found in a neighboring lake, but on the whole it always follows 
along certain great lines and shows that lakes can be grouped into classes 
according to its maj or vari- _ , 

ants. Only a little of this C _ _ Q ^ _ . . . T_ _ 34 36 

story is now known, and 
many years of detailed 
work will be needed be- 
fore even its larger facts 
are fully ascertained and 
justly interpreted. But 
from the few diagrams 
which I have given one 
may see that lakes present 
to the student a vital 
story, as definite, as vari- 
able, and as complex as 
is that of a living organ- 
ism; a story to be followed by means like those needed to work out biological 
life histories, and one whose interest is such as to claim far more attention 
from science than it has received. 



Fig. 17. — Beasley Lake, August 4, 



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—otter Lake, August 4 



GASES IN WATERS OF "^^SCONSIN LAKES. 



I29I 



PRACTICAL IMPORTANCE OF THE SUBJECT. 

If this scientific interest were all that the story affords, however, I should 
not have brought it to the attention of this congress, whose interest rightly lies 
in the fisheries. But these changes, which go on in the water of the lake, affect 
not only the life of lower organisms but also that of the higher ones, including 
the fish. No facts of environment show more clearly than do these how life 
determines its own conditions. On the presence of a large or a small quantity 
of plankton in the upper waters may depend the conditions which make the 
lower water habitable or uninhabitable. The relation between the volume of 
the lower water and the quantity of decomposing matter discharged into it 

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Fig. 19. — Silver Lake, August 2 

determines whether this lower water shall be filled with animal life and support 
a relatively abundant population of lake trout and whitefish, or whether life of 
all kinds shall cease abruptly at the thermocline, or whether a scanty plankton 
shall indeed leave abundance of oxygen in the lower water but provide a supply 
of food for a scanty higher life. Thus the annual history of the lake discloses 
facts that are fundamentally important in determining the amount and kind of 
life which the lake may support and that which may wisely be introduced into it ; 
and it becomes plain that a knowledge of them is indispensable to an intelligent 
use of the waters of the lake by those concerned in increasing the supply of fish. 
In other words, it seems clear that a knowledge of lacustrine physics and 
chemistry is just as necessary to the best economic utilization of the waters of 



1292 BULLETIN OF THE BUREAU OF FISHERIES. 

the lakes as a knowledge of soil physics and chemistry is to the best agricultural 
use of the land. The problems of the lakes are complex and are not easily 
solved, but they are far less complex and much more easily solved than are the 
corresponding problems of the soil. This nation and the several states are 
spending hundreds of thousands of dollars annually in studying the soil. This 
expenditure is fully justified, not only by its scientific results but also by its 
practical consequences. Little or no time or money is now devoted to the 
similar study of the waters of the lakes. Yet no one who has followed investi- 
gations of this kind can doubt that if the lakes could be studied on the same 
large scale and with the same careful methods as those applied to the study 
of soils, results of great economic value would be obtained. It was years before 
the study of physics and chemistry of soils promised large economic results. 
Valuable practical hints have already come from the brief and imperfect study 
of the lakes which our survey has made, and the present situation of our knowl- 
edge indicates that a wider and more systematic study than we have been able 
to undertake would ultimately lead to far larger and more important con- 
clusions. Such a study is greatly needed. The culture of fish in the innumer- 
able inland lakes of this country should rest on the basis of scientific knowledge 
at least as broad and as complete as that which underlies the cultivation of our 
farm products. We who have in charge the maintenance of a public interest 
so extensive and valuable as is that of the fisheries are most of all concerned 
in the acquisition of that knowledge which is the only true guide of practical 
affairs. 



DISCUSSION. 

Mr. J. J. Stranahan (U. S. Fisheries Station, Bullochville, Ga.). I would like to 
ask Professor Birge a question or two. It is not closely related to this subject, although 
not entirely foreign. I desire to ask if you have had any experience as to the plankton 
and the relative amount of crustaceans and other animal life that is in soft and hard 
waters. 

Professor BirgE. Yes; although the matter can not be finally settled. It is a 
condition well known to European investigators. The hard-water lakes are much 
richer in plankton on the average than the soft -water, but you can not make the state- 
ment that every hard-water lake has more plankton than any soft-water. 

Mr. Stranah.an. At Guilford, in England, south of London; at Castalia, in Ohio; I 
think at Northville, in Michigan, and wherever I have known of exceedingly hard water, 
full of lime and other salts, there has been an excess of plankton. I collected plankton at 
CastaUa to take to the World's Fair at Chicago, and with pretty carefully conducted 
weights the amount of crustaceans exceeded the amount of mosses and aquatic plants 
in which they were congregated when taken from the water. That water is so rich in 
lime and magnesia that it makes stone of a shingle in a year, and that is probably the 
greatest trout preserve in the world. At Bullochville, Ga., where I am now, our water is 
practically aqua pura; we can use it in photographic processes; it is exceedingly soft. 
We have put mollusks in it, but the different little periwinkles and other shell-covered 
species die in a few months, and it is not conducive to fish culture. We took two 
carloads of cement and buried it in our spring, and we thought we could see a marked 
increase in the growth of some kinds of vegetation, to say nothing of small water animals 
that grow in it. So I am a great stickler for the idea that we ought not to put fish 
hatcheries where there is not a large amount of calcareous material in the water. 

Professor Birge. I wanted to talk about that, but with the Hmitations on the 
time I could hardly get to that part of the subject. 

Doctor NoRDOvisT. Those investigations Professor Birge has made are of the 
greatest importance in fish culture in lakes. I am of the same opinion as Professor 
Birge, that many of the disappointments that we have in fish culture are due to lack of 
knowledge about the amount of oxygen and the biological conditions of the lakes. 

I would only ask Professor Birge about some slight points here in his investi- 
gations. At what time in the day was the amount of oxygen determined? 

Professor Birge. We have made a great many attempts to discover diurnal 
variations in oxygen, but it is a very rare thing to find any difference in the results 
obtained from tests made in early morning, late afternoon, and late evening. We 
have continued the tests throughout the twenty-four hours. We have found very 
small, hardly perceptible, diurnal differences. I have received, since I came to this 
congress, a letter from my assistant, Mr. Juday, to whom much of this work is due, 
telling me that he had found such a difference in Lake Mendota. 

Doctor Nordovist. That is just what I mean with reference to the investigations; 
it ought to show a dift'erence, and I think that the curve that you have given in many 
of your lakes at the depths of six, seven, to ten meters may perhaps 

Professor Birge [interrupting]. We have spent from two to three weeks hunting 
for diurnal changes right on that point. I put a party on those lakes — Otter Takes — 
and we got negative results all the time; the curve remained substantially the same. 

1293 



1294 BULLETIN OF THE BUREAU OF FISHERIES. 

Doctor NoRDQVisT. It is very interesting to hear that. Then I would be glad to 
learn in what way the oxygen was determined. 

Professor BirgE. In two ways: One diagram showed an oxygen line determined 
by boiling; and in the other it showed oxj'gen by Winkler's method of titration, or by 
one of the modifications of Winkler's method, which is a standard in the books. 

Doctor NoRDOVisT. Oxygen by the Winkler method? 

Professor BirgE. Yes, depending on the liberation of iodine and sodium at the end. 

Doctor NoRDOViST. How was the water taken up? 

Professor BirgE. The water was taken up by a pump and hose, the latter being 
lowered to the proper depth, and the water brought up and kept completely out of 
contact with the air, so that where there was no oxygen we had like results always. 

The President. Are there others who will contribute to the discussion of this most 
interesting paper? 



LIBRARY OF CONGRESS « 1 



III 

10 029 714 161 2! 






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